Understanding about twins has always been a challenge for the researchers. Our modern science has come up with many findings on this topic. In this article, I'm going to talk about a mysterious twins village present in Kerala, India. I will also provide some details on general information about twins towards the end of this article. 
  
In Mallapuram district of Kerala, there is a village called Kodinhi. This village is attracting many researchers from all over the world. The mystery still remains unsolved. So what is the mystery here? Well, the village has a population of about 2000 families and out of which there are nearly 400 pairs of twins. In the year 2008 on an official record, there were about 280 pairs of twins in this village. The numbers have been increasing in the following years after that. Compared to national level twin births of about 9 among 1000 births, Kodinhi is creating records with 45 twins in 1000 births happening there making the village the largest twin birth zone in the country. A research [[1]](https://www.researchgate.net/publication/303912139_Village_of_Twins_A_Mystery) was conducted in the month of April - June 2016 and the following outcome was given as conclusion. 

> To conclude, the etiology behind the high rate of twinning in this particular village in Southern India is still a mystery to the scientific world.

![](https://steemitimages.com/DQmfBax8yvkjC93JSAQyAcpnrMqUUVsRsUaiAXjvM8ZqZyB/image.png)

<center>[Image Source - Pxhere - CC0 License](https://pxhere.com/en/photo/903252)</center>

Apparently, Kodinhi is not the only place in the world with the largest number of twins. There are few more places identified with similar mysteries. 
  
* Hung Loc commune in Hung Hiep from South Vietnam 
* Igbo-Ora in Nigeria 
* Cándido Godói in Brazil 
  
It is also believed that the population of twins is increasing all over the world. Australia is another place where multiple births in one pregnancy are increasing in the last few years[[2]](http://www.kidspot.com.au/birth/pregnancy/pregnancy-health/twins-and-more-all-about-multiples/news-story/35133c2fc582e77e2f1a48e9f8b634d8). We are always more excited to know and understand more about twins. 

Leaving the mystery part aside for a while, let's see why twins are amazing and the types of twins science have discovered so far. 
  
## Why twins are amazing? 
  
This question can be easily answered by the parents who already have twin children. Apart from the fact that some mischievous twin may not be pleasant for their parents on some tough days, they are usually amazing. Let's go through some facts. 

![](https://steemitimages.com/DQmQiX4yCzZz44BaqV7bj4DyB1S5VHvNUHpjr4MGNw5brQw/image.png)

<center>[Image Source - Pixabay - CC0 License](https://www.pexels.com/photo/2-girl-on-grey-and-pink-dress-on-daytime-160504/)</center>
  
* Twins from the day one they are formed, they grow up with a company. Together they usually innovate and explore the world. 
* 40 % of twins in the world communicate to each other in their own language which is unknown to others. [[3]](https://www.ncbi.nlm.nih.gov/pubmed/3434134)
* They have a very good understanding among each other as their thought process will be similar. 
* About 20% of twin population is left-handed. Scientists are still exploring why it happens to be like that. 
* In spite of having same genetic structure, the fingerprint of twins differ from each other even in the case of identical twins. 
* About 25% of identical twins are mirror image twins developing some attractive characteristics. Usually, one will be left-handed and another will be right handed. All the internal organs will be reversed in one of the twins. 
* Even separated twins develop same characteristics. [[4]](http://www.bbc.com/news/av/world-europe-34209018/twins-reunited-after-70-years-apart), [[5]](http://abcnews.go.com/Lifestyle/twin-sisters-separated-birth-reunited-gma-reflect-year/story?id=52231569)

## Types of Twins
  
### Fraternal Twins or Di-zygotic Twins
Fraternal twins are the most commonly seen twins born out of two different sperms and eggs. They can either be of the same gender or different gender. In medical terms, these twins are called as di-zygotic twins. The name is derived from the fact that they are developed from two zygotes. It can be said that they are siblings born together in one pregnancy with a 50 percent chance of genetic share. Unlike the identical twins, they will not be having a perfect genetic match. Hyperovulation is a condition where women release multiple eggs in every cycle. Thus, women who hyper ovulate have high chance to get fraternal twins. 

![](https://steemitimages.com/DQmUFZHMZX4jCwkGtbo6jApY4zGNU8BXw3SLKqey32NoHyD/image.png)

<center>[Image Source - Flickr - CC0 License](https://www.flickr.com/photos/ameriswede/6886780208)</center>

The hyperovulation can be a genetic trait passed from one generation to another generation. Women with hyperovulation trait can pass the trait to her daughter. There are also cases where even male carry the hyperovulation trait as they have both X and Y chromosomes. This condition can create a higher chance of having fraternal twins. Father having hyperovulation trait in his gene will not be the determining factor for having fraternal twins as during pregnancy the formation of the zygote is dependent on mother's ovulation pattern. There is just a possibility that the father can transfer the skill to his daughter to be able to hyper-ovulate. 

### Identical Twins or Mono-zygotic Twins

Mono-zygotic twins are the most interesting twins. Identical twins are formed out of one zygote. After the conception process, one zygote splits into two parts and develops to become two embryones. Just because identical twins are formed with the split of one zygote, they carry the same genetic information. Their DNA patterns will be identical. It is quite a mystery how monozygotic twins are formed as there is no literal necessity for an egg to be split into two. The formation of identical twins with egg splitting is considered to be a malfunction in the proper process. 

![](https://steemitimages.com/DQmXf2PNJ5qQJ27VQzHbNEMCWc8yJFkYGZu8BTZXfQFovQv/image.png)

<center>[Image Source - Wikimedia- CC0 License](https://commons.wikimedia.org/wiki/File:CamillaRebeccaRossoMarch09.jpg)</center>

Unlike fraternal twins, the hereditary trait cannot be a factor for identical twins. However, there are also cases where identical twins run in the family for generations but in general, it is considered to be a pure coincidence. It is quite interesting to always observe the actions of identical twins. One can easily identify identical twins by their looks. However, there are some methods to determine whether they are identical or fraternal. One of the most interesting facts is that identical twins don't have same fingerprints. If they need to be distinguished, fingerprints can be used as their looks and DNA can be identical but not their fingerprints. 

### Half-Identical 

The possibility for Half-Identical twins was identified recently in the year 2007 by the researchers and scientists. These twins were identified to have identical properties from mother's side and only 50% of traits from father's side. They are somewhere between identical twins and fraternal twins. This type of embryo formation is quite rare. Half-Identical twins are formed when two sperms fertilize one ovum and in-turn split into two different embryones. Finding a semi-identical or half-identical twin can be a real challenge for the researchers to carry out their further study to understand this mystery. 

![](https://steemitimages.com/DQmZwF9EJBB9DNM1upyMtT2T1TkvqutSnk8hPoB43BbRWEh/image.png)

<center>[Image Source - Pixabay - CC0 License](https://pixabay.com/en/brothers-twins-portrait-835169/)</center>

### Mirror image twins 

If twins face each other and appear to be exact reflections of each other then they are known as Mirror image twins. They are identical twins or monozygotic twins fertilized from the same egg. About 25 percentage of monozygotic twins are born as mirror image twins. During the development phase, there is a possibility that the twins can develop asymmetric features that are like mirror image reflection. Some of the characteristics and physical features of this twin can be like a mirror image reflection where if one is comfortable using left hand, the other will be comfortable using right hand. The birthmarks will also be visible on opposite sides of the body. The pattern of hair growth will also be in the opposite direction. There will also be cases where the organ positioning will also be reversed. With these physical characteristic features, it may not be right to say that Mirror image twins are totally a new type of twins but they are a bit different from other identical twins. 

![](https://steemitimages.com/DQmVNtKyZL8TcN55pgBgP3xFbpwic1ebkc4pUZn1Ae2euH9/image.png)

<center>[Image Source - Wikipedia - CC0 License](https://en.wikipedia.org/wiki/File:Reflected_Twins.jpg#/media/File:Reflected_Twins.jpg)</center>

### Mixed Chromosome twins 

It is quite rare to see such type of twins. In the case of mixed chromosome twins, two sperms fertilize two different ova initially and later it fuses to form embryo with different chromosome patterns. In this type of twin formation, there is again a possibility for one to be XX chromosome and another to be XY chromosome. 

### Superfecundation 

This is a case where the twins are fraternal twins where sperm from one father fertilizes one ovum and sperm from another father fertilizes another ovum thus developed as twins. This can be a case when a woman is in a relationship with two men at the same time and giving birth to their offspring in one pregnancy. It will be quite interesting to see such twins. Especially when one lover of the mother is a black and another lover is a white, the pregnancy can produce twins where one child will be black and another will be white. 

![](https://steemitimages.com/DQma1xJGu3hV64YiD93X5ojdxVjeyJmJFxMcFH19jme2BcB/image.png)

<center>[Image Source - Pxhere - CC0 License](https://pxhere.com/en/photo/982278)</center>

### Superfetation 

This is a process in which twins are formed when an embryo is already growing. In a case where there is already a conceptus present in the womb of the mother, fertilization of another Ovum by a sperm takes place and start to grow as an embryo. 

Out of the above-mentioned twin types, Fraternal and identical twins are very common and it is very rare to see the other types of twins.

**References:** [[1]](https://www.researchgate.net/publication/303912139_Village_of_Twins_A_Mystery), [[2]](http://www.kidspot.com.au/birth/pregnancy/pregnancy-health/twins-and-more-all-about-multiples/news-story/35133c2fc582e77e2f1a48e9f8b634d8), [[3]](https://www.ncbi.nlm.nih.gov/pubmed/3434134), [[4]](http://www.bbc.com/news/av/world-europe-34209018/twins-reunited-after-70-years-apart), [[5]](http://abcnews.go.com/Lifestyle/twin-sisters-separated-birth-reunited-gma-reflect-year/story?id=52231569), [[6]](https://www.thenewsminute.com/article/kodinhi-kerala-village-400-pairs-twins-continues-be-mystery-researchers-61083)

**Note:** I was unable to share any image from Kodinhi Village in this article as I was not sure about the license information of the images available in Google. If you are interested in seeing the images from Kodinhi village, you can google them. 

Hope you found the article interesting!

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gif courtesy: @rocking-dave
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